Condensed Consolidated Statements Of Equity (USD $) In Thousands		Total	Common Stock [Member]	Capital Surplus [Member]	Accumulated Other Comprehensive (Loss) Income [Member]		Retained Earnings [Member]	Treasury Stock [Member]	Noncontrolling Interests [Member]
Balance at Dec. 31, 2013		$ 1,479,626	$ 676	$ 408,083	$ (65,777)	[1]	$ 1,133,873	$ (10,590)	$ 13,361
Net income including noncontrolling interests		41,842					41,261		581
Other comprehensive income		445			445	[1]
Common stock issued under share-based compensation plans	[2]	7,390	4	7,098				288
Common stock issued under employee stock purchase plan		866		866
Common stock dividends		(5,353)					(5,353)
Repurchase of common stock		0
Distributions to noncontrolling interests		(900)							(900)
Share-based compensation expense		2,598		2,598
Balance at Mar. 31, 2014		1,526,514	680	418,645	(65,332)	[1]	1,169,781	(10,302)	13,042
Balance at Dec. 31, 2014		1,429,387	636	227,885	(83,197)	[1]	1,280,991	(10,302)	13,374
Net income including noncontrolling interests		32,710					32,849		(139)
Other comprehensive income		723			723	[1]
Common stock issued under share-based compensation plans	[2]	323	2	321
Common stock issued under employee stock purchase plan		1,018		1,018
Common stock dividends		(5,039)					(5,098)
Common stock dividends, accrued dividend shares				59
Repurchase of common stock		(21,148)	(5)	(21,143)
Distributions to noncontrolling interests		(7,500)							(7,500)
Share-based compensation expense		3,000		3,000
Balance at Mar. 31, 2015		$ 1,433,474	$ 633	$ 211,140	$ (82,474)	[1]	$ 1,308,742	$ (10,302)	$ 5,735

[1] Represents cumulative foreign currency translation adjustments and post retirement liability adjustments.

[2] Includes the tax benefit associated with share-based compensation of $0.9 million and $4.9 million for the three months ended March 31, 2015 and 2014, respectively.